My U.S. Pat. No. 4,079,865 and my U.S. patent application Ser. No. 851,277, now U.S. Pat. 4,146,155, show different novel and advantageous pumping systems for dispensing a liquid or other flowable product from a container. In both the pumping system has a pressurizing chamber for receiving the product from the container through a first check valve, a storage compartment for receiving the product from the pressurizing chamber through a second check valve, and a restricted discharge orifice for passing the product from the storage compartment. In U.S. Pat. No. 4,079,865 the pumping system is operated by a pivoted lever and in U.S. Pat. No. 4,146,155 the pumping system is operated by a reciprocable plunger, both manually actuated.
Both of the aforementioned pumping systems suffer from a tendency to produce a pulsating discharge of the product from the discharge orifice because of pressure variations in the storage compartment at different times during each cycle of operation of the manually actuated lever or plunger. A more nearly constant discharge of the product would be achieved if the pressure in the storage compartment were more nearly uniform throughout each operating cycle.
Also, with both of the aforementioned pumping systems difficulties sometimes arise when the user attempts to prime the system by purging it of air when it is used the first time. The air pressure developed by actuating the operating lever or plunger may be insufficient to uncover the outlet opening from the storage compartment to the discharge orifice.
In addition, in both of the aforementioned pumping systems the discharge orifice moves up and down during each operating cycle of the lever or plunger, and some users may find this objectionable.